Move the SplatNet user agent string to .env

This way, if someone else uses the library it won't be attributed to splatoon2.ink.

.env.example

@@ -1,6 +1,9 @@
 # Nintendo SplatNet 2 "iksm_session" value
 NINTENDO_SESSION_ID=
 
+# (Optional) User agent string for SplatNet requests
+SPLATNET_USER_AGENT=
+
 # Google Calendar ICS URL for Salmon Run schedules
 # Provided by: https://www.reddit.com/user/thejellydude
 SALMON_RUN_CALENDAR_ICS_URL=https://calendar.google.com/calendar/ical/7e5g474p0ng7vaejkg3mkomhks%40group.calendar.google.com/public/basic.ics

src/updater/splatnet.js

@@ -4,7 +4,7 @@ const path = require('path');
 const axios = require('axios');
 
 // SplatNet2 API
-const userAgent = 'splatoon2inkbot/1.0 (+https://splatoon2.ink)';
+const userAgent = process.env.SPLATNET_USER_AGENT;
 const splatnetBaseUrl = 'https://app.splatoon2.nintendo.net';
 const api = axios.create({
     baseURL: `${splatnetBaseUrl}/api/`,